userguide WIEN2WANNIER: From linearized augmented ... - WIEN 2k

to create the subdirectory subdir with all the required file for the workflow below. Thus, onewien2k calculation can be the starting point of multiple different w2w (and consequently wannier90)runs. Alternatively, the steps can be done in the original wien2k directory (note that theoriginal .vector file will then be overwritten in the process)The initialization of the interface can be done either by single commands or by the scriptinit w2w or init w2w -sp for spin-polarized casesInitialization (init w2w)The script init w2w takes the following stepsksym for wannier90 a non-symmetrized k-mesh is required. Therefore the struct file is copied tocase.ksym. The number of symmetry operations in case.ksym has to be set to 1 and thefirst operation has to be the identity(ones in the diagonal, all other values zero).kgen standard wien2k generation of a k-mesh (with -so switch to deactivate the inversion operation).The size of the mesh influences the quality of the localization and visualization ofWannier functions. Remark: The interface was only tested with k-meshes without shift.find bands(optional) The energy window to be used for the projection on the Wannier functionsis determined by the (wien2k) index of minimal and maximal included Bloch states. Byuse of find bands this information can be extracted from a previous lapw1 run (that is fromcase.output1), when the corresponding energy window is given by [Emin Emax] (in eV withrespect to the Fermi energy). A good strategy is to look at a spaghetti or tetra outputand to choose the energy window of interest.write w2win this utility program writes the actual input file for the interface case.w2win. Theindex of Bloch bands (internal wien2k numbering) and the number of target Wannier orbitalshave to be specified. Additionally, the initial character of the Wannier functions has to begiven in terms of atomic orbitals labeled by the atom where the orbital is centered and bythe angular momentum quantum numbers l. The numbering of atoms is again the internalwien2k serial numbering, e.g. in the case of TiC, an initial function located at the C atomwith p character requires the input 2 p . The projective angular momentum quantum numbersm are chosen automatically, but can be changed by direct manipulation of the input filecase.w2win.write win A utility program to write the input file for wannier90 case.win. Though write winrequires no obligatory input, the produced file can be adapted to specific needs (e.g. settinga frozen energy window for the disentanglement procedure in wannier90).wannier90.x(preliminary run) wannier90 requires the input data to be given on a special k-meshwhich includes information with respect to nearest-neighbor k-points. A preliminary call ofwannier90 with the option -pp stores this mesh to the file case.nnkp .write w2wdef Based on wien2k the interface w2w also requires a file where the I/O file informationis stored, which is called w2w.def.w2wAfter running init w2w, one can proceed:x lapw1 before the actual interface run, the eigenvectors and eigenvalues for the new (nonsymmetrized)k-mesh have to be computed.w2w case this computes the files case.mmn, case.amn and case.eig for a wannier90 computation(information of the run is stored to case.w2wout).In case the wien2k and the wannier90 bandstructure are to be compared, the utility program3